One gene found to command many others to build a wing

Some genes are born to lead. Others, apparently, are born to follow.

That scenario, where a single gene orchestrates the construction of a fruit fly wing by commanding a network of many other genes, is described in the April 13 edition of the journal Science by a team of researchers at the Howard Hughes Medical Institute at UW–Madison.

The finding is important because it helps define the organizational flow chart for genes whose job it is to build structures. These genes, known generally as selector genes, are critical to the building of wings, legs, eyes, antennae and more. And the implications of the discovery very likely extend far beyond fruit flies to other animals, including humans, says Sean Carroll, a study author and developmental biologist.

“Of all the genes in the genetic tool kit, very few shoulder the responsibility of commanding the development of an entire structure,” Carroll says. “Genes that are involved in making structures need to know how they’re going to act. Here’s a gene that does that and it gives us our first concrete look at how this process works.”

The gene, known to molecular biologists as “scalloped,” is responsible for making a protein that seeks out and turns on all the genes that do the heavy lifting of producing and organizing cells to form a wing. The protein produced by scalloped binds to certain segments of the fruit fly genome and activates and regulates target genes within those segments, Carroll says.

In fruit flies, the genome is composed of about 13,000 genes. Of those, perhaps less than a dozen behave like scalloped, making these boss genes critical nodes in the process of animal development, Carroll says.

Lead authors are Kirsten A. Guss and Craig. E. Nelson. Co-authors include Angela Hudson, Mary Ellen Kraus and Carroll, professor of genetics and molecular biology at UW–Madison.